Torque measuring device



C. A. SHANK TORQUE MEASURING DEVICE Filed Jan. 2s, 1944 INVENToR. Uffa/P0 ,4. JAM/wf A.: 7l, :m Pd,

wxmm@ al@ Patented Oct. 2, 1945 IOBQUE BIEASUBING BEVICE Clifford A. Shank, Jackson Heights, N. Y., assignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Dela- Application January 28, 1944, Serial No. 519,745

. (Cl. 'I3-M6) 12 Claims.

ing of the shaft causes'a displacement or these extending portions relative to one another. li the portions are incorporated in a suitable elec vtrical circuit, the resulting change in capacity between the portions can he employed to ailect the electrical characteristics of the circuit. Since the change in capacity is a function oi the torque on the shaft, a measurement ci the latter may be obtained directly on a suitable indicator.

in mechanisms or" the above type it is necessary thatdaoth niemeer portions constituting the condenser plates rotate with the shaft. ,Since the remainder or" the circuit, as well es the indicating apparatus, is usually stationair, sonic form of electrical coupling between ports is necessary. This is customarily obtained Toy orloviding o. rotating coli inductively coupled to a connected to 'the 'latter to stationary coil, the former coing one oi the condenser plates and the measuring circuit.

lotvever, certain difficulties ced in such arrangements.

noviding proper coils. Another d .dcuity is the any shift in relative coil position the .necessarily delicate coupling ratiothe rotating and stationary coils. problem is that of providing a torque 1Per coil construction that will incorporate the f meJ shove reatures and still permit the parts to he quickly and easily assembled, or as readily taken apart for inspection and/ or repair.

'in one type ci coil shielding construction pronosed, two cylindrical shield sections are joined together by means such es soldering. Since the solder does not completely nil the space between the sections, a number of air gaps result. Furthermore the solder is necessarily unevenl'y distributed along the junction o the sections. All of the above tends to create an imbalance ci the shielding which detracts from the accuracy of the measurements.

Furthermore, when coaxially mounted rotating and stationary coils such as used in many tion in which all oi the c torque meters are in position, it is necessari7 that any predetermined coupling ratio between the two ce maintained under all operating condi tions. .The reason for this is obvious, since a change in such ratio will cause a change in measurement which will naturally be attributed to an actual change in torque. Prior art devices are generally lacking in positive means for preventing these undesired coupling changes.

Not only must the above conditions he fulfilled hut the resulting arrangement must in addition loe readih; demountalole. In the aforementioned proposed design in which two shielding sections are joined hy soldering, ior example, itis dimcult to subsequently separate the sections.

' @ne object of the present invention, therefore,

to provide, in a mechanism having iiXed and rotating' coils, an improved form of shield for lthe rotating coil member that is electrically halanced throughout.

A further object oi the present invention is to provide means for preventing undesired `coupling changes between lined and rotating coils due to a lateral change in position of the fixed coil relative to the rotating coil.

A still further object oi the invention is to provide a rnerrllcer for shielding a 'plurality of longitudinally spaced-apart coil portions one iron] the other, this member being constructed as a single unit having integrallyforrned -orojections coocerating with the coil support to substantially enclose each coil tion.

in addi"ional ooject ci an improved forno othe invention is to protorque meter con rte may he quickly; easily assembled and dis enabled.

@ther objects and advantages will he anna rent from 'the following description and from the dran/i Q, in which:

Fig. l shows a longitudinal section or' an irngoroved iorrn of torque meter construction in accordance with the present invention; and

Fig. 2 is an end view of the rotating coil shield oi l alone lines also showing the method oi grounding such shield to the torque tube.

in the drawing id designates a powertransmitting member the torque on which is to he vide measured. it Wl ce understood that althoueflfl for example as-a hollow cylindrical shaft, may' obviously ce substituted therefor. The hanged end portion il of the member i0 is adapted to he y tion II of power-transmitting member IU.

connected to some element of the power source itself such as the flywheel. The other end of the member I is connected to a load.

Securely joined to power-transmitting member I0 at some point thereon removed from ange II is an inner torque tube I2, this junction of member I0 and tube I2 being made in some preferred Amanner as by a shrink t. As shown in the drawing, torque tube I2 is substantially coaxial with member Ill.

When rotating under load conditions, an angular displacement will be developed along powertransmitting member I0 between the point at which tube I2 is connected, on one hand, and the nanged end II on the other. With respect to torque tube I2, however, this tube is secured at but one point (that point being the connection to power-transmitting member Ill), and no appreciable displacement will occur along its length.

A condenser assembly generally indicated as I3 in the drawing is provided to make use of this relative displacement of members Ill and I2. This condenser assembly is of known design, and will not be described in detail. It is suiclent to say that one set of plates ISA.v of the assembly is joined to, and rotates with, the flanged end por- Other plates I3B and ISC are joined to and rotate with torque tube I2.

Plates ISA are grounded. Plates I3-B are connected to the socket I d of a plug and socket assembly.l Plates ISC are connected to the socket I5 of a second plug and socket assembly. Thus when power-transmitting member Ill is under load, a displacement will occur between plates ISA, on one hand, and plates ISB and ISC on the other. I'he change in capacity of the condenser assembly I3 as aresult of this displacement is used to obtain a measurement of the torque on member III.

To provide means for conveying the capacity changes of condenser assembly I3 to an electrical measuring circuit (not shown), two coils are provided. Each of these coils is o! conventional helical shape and is divided longitudinally into two spaced-apart portions. One of these coils, having portions ISA and IBB, iscoaxial, and rotates synchronously, with torque tube I2. The other of the coils, having corresponding longitudinally spaced-apart portions IIA and HB, is coaxlally mounted with the rotating coil but is itself secured against rotation in a manner hereinafter to be described.

A hollow cylindrical coil shield 20, preferably i formed of some suitable shielding material such as brass or aluminum, is coaxial with coil portions IBA and IBB. This shield 2li encircles. these coil portions, and is designed with three integrally-formed inwardly-projecting ribs 2 I. These enclosed spaces respectively containing the coil portions ISA and ISB.

The coil shield 20 has outwardly flanged ends 22 forming extensions of the end ribs 2l. outer diameter of these anged ends 22 is approximately equal to the inner diameter of torque tube I2, so that these elements are in close i'ltting relation. The rotating coil assembly is thus positioned to eliminate radial movement within the torque tube I2.

To fasten the coil shield 20 securely to the coil support I8, a plurality of screws 23 are employed. To permit use of these screws, the ridge I9 of coil support I8 nearest the free end of torque tube I2 is provided with a flanged extension 24, and an annular recess is cut out of the corresponding rib ZI of shield 20 to receive Vthis extension 24. 'Threaded openings in rib 2| then permit the screws 23 to secure together` the rib and the anged extension. Y

To position the rotating coil assembly against longitudinal movement within torque tube I2, a

pair of washer units 2E are provided respectively securing ring 28 thus acting to compress together the sealing washers of the units due to the limiting action of shoulder 26.

One end of each of the coil portions ISA and IBB isrgrounded to the coil shield 20, the coil portion ISA being grounded by a lead 30 passing through an insulated opening 3| in shield 20. and being secured to a anged end 22 of shield 20 by a lug 32. One end of coil IBB is grounded in a similar manner by a lead 33 joined to a lug 33A. The ungrounded end of coil IGA is connected by a lead 3d to a plug 35 receivable in socket I4. The ungrounded end of coil ISB is connected in a similar manner by a lead 36 to a-plug 3'I receivable in socket I 5. Leads 33, 34 and 36 pass through insulated openings in shield 20 similar to the opening 3l.

By the above mode of assembly, and particularly because of the close llt between the corresponding ridged portions of the coil support and the ribs of the shield, a shielding for the rotating- .40. A bearing collar M serves to position in rotational relation with torque tube I2 a tubular mounting member d2, this member d2 being of course coaxial with tube I2. y

Encircling mounting member I2 is a coil form 43 of some suitable insulating material such as Bakelite, on which are wound stationary coil sections I'IA and I'IB. -One end of coil form 43 lies adjacent the turned over end portion of collar Thev 4l,'this collar serving to space mounting member 42 in fixed position radially with respect to coil support I8, and to position coll torm 43 in xed position longitudinally in respect to coil support I8, assuming that some means tend to keep the end of coil form 43 adjacent collar 4l. This latter means will now be described.

Partially encircling the outer end of mounting member 42 is a tubular spring holder 44 having therein a spring 45. @ne endof spring liolcier 44 is securely :affixed to the end oi mounting member 42 by some preferred means such as silver soidering. This same encL of holder $4 presses against the .outer end of coil form 3 es illustrated. The other end of holder 44 partially encircles in telescoping relation a cylindrical portion oi e member is serving as a connector to some stel tionary external device such as part of an engine assembly. As shown, this member 6 forms part of e propeller shaft oil inletr but obviously may be any other element connectobie to astetionary en terrieri device.

Spring #iii thus provides means for keeping the sietiox'ierg17 coil assembly under pressure the bearing collar ti, thereby prevents any l rele-,tive longitudinal movement between coil supsort and coil forni fit during rotation ci tine former. 'I'.i'ie coupling between tiiecoil portions iii euri ill-fi, therefore, ive-ll es between coil portions (EEE and i'i'l-, will not be lznciesi-rsbiy affected by vibre-tion er other tendine produce o relative ioiisitiiclinel movement be tween tlie iixeol one rotating coils.

l longitudinal slot out in the interior sortsce of coil forni d3, end e sin il@ riding in this slot and. receivebleiri eri opening in iiiountine member it tennis to prevent env reist-.ive mooier disolecement oi elements and has been ststed simile holder and stotieriary connector member Il@ ere telescoping relation. To prei/'ent rotation of holder lli, e pet-ir of longitudinal slots are out in the spring bolder, and a pair of pins positionecl in connector member et respectively ride in these slots. A retaining ring 5i limits the extent to which members 44 and t@ may be drawn apart.

One end of each of coil sections i'iA end i'IB is respectively connected to one oi o, peir of shielded transmission line conductors 52, the connections being preferably molded within the Bakelite coil form lit. The other end of each of coil sections iiA and i'il is grounded to the shield of the transmission line conducto-rs.

Referring now to Fig. 2, there is shown the inner torque tube and the rotating coil shield of Fig. l teiten along the line 2 3, with the coil surn port it and its flanged extension 2t removed.

As shown in Fig. 2, one outwardly-named end Eli oi coil shield 2li is provided with two oppositeiy-disposed openings t@ therein. The other flange is provided with like openings, as can be seen from Fie'. l. The purpose oi openings i365: of Fie. 2 is to permit clues anni to be reu spectiveiy inserted iii sockets it and i5 eiter the rotating coil assembly is placed Within torque tube iii, this insertion beine' accomplished lay-means of long-ngered pincers which can reach the plugs 3E and 3l through openings M before washer unit and securing ring 2E are in place.

Fig. 2 also shows a method of positively grounoi= ing the coil shield 2Q to the torque tube it. The end ilange 22 of shield 2t is provided with a niche on the periphery thereof. A corresponding' tab or projection 56 on the inner surface of torque tube i2 ts into this niche 55. A pin-shaped Opening in tab it is adapted toreceive a wire El' which is then soldered in place.

A further opening |56 is provided in flange 22 adjacent tab 56. Near the edge of this open ing 58 a soldering lug 5! is secured to flange 22 by means such as a bolt lli. After the rotating coil assembly is in place within the torque tube i2, (tab 5E now being in place within niche 5e), the loose end of wire 5l is soldered to the ills 5t through' the opening til. Thus e, positive ground connection is obtained for the shield 20, end also for the rotating coilv ieacls in and iii which are secured to the shield by means of lugs til and 33A. It should also be noted that in addition to serving as part of ground consection, tab 5G together -with niche 55 prevents any relative rotation of shield il@ and torque tube i2.

'While i3 lieve described above tire principles of my invention in connection with specific apparatus, it to be clearly understood tiret this description made only by wey of exemple and not es c, iir tation on the scope ci my invention es set forth the cioiects of im' invention and the accompsovrie' claims.

piling device inclu#l g e, fired coil ting coil, seid roteting coil being formed in o longitudinally sections, seid i sed coil being likewise formed irl tivo longitudinelly specedeep" sections, the two coils being coesrialiy mounted so the sections of tile r coil ere respectively coupled to tlie sect is oi tile fixed coil, the coinbinstion oi e tubular support on which is wound said rotating? coil seid support liei iv en annular ridge on. the outer: surface te 'cof intermediate said sections end a further pair of ridges respectively adjacent the ends of seid coil sections, and hollow cylindrical shield substantially encircling seid tubular suroort, said shield having three integrally-formeel ibs on. the ner surface thereof positioned lor respective 'eri-= gagement witir the ridges oi said coil support, omi means attaching said shield to said coil support.

2. i coupling device according to claim l, lurtlier comprising e tube of insulating material on which is wound said fixed coil, a hollow cylindricai support within said tube, s, tubular spring holder secured to one end of seid support, a, spring' Within seid holder, a stationery positioning member for said spring bolder, seid sositioning mentx ber having a cylindrical portion engaging seid spring holder in sliclable teiescoping relation therewith, means preventing relative rotation between said spring holder and seid positioning member, means at the opposite end of said support from seid spring bolder for engaging said tube to limit the longitudinal movement thereof, whereby seid spring will tend to com press seid tube 'between seid last-mentions@ ineens and spring holder.

er ln combination, a cylindrical coil form oi' irisulating mafrial, said coil form having three spaced-apart emular ridges on the outer sur face thereof, a of coils, said coils beine respectively Wound on said torre in the spaces between said ridges, a cylindrical shield co-am'ai with said coil Aforro and enclosing seid coils, said shield being constructed es e, single piece of conducting material having its ends flanged reciielly inward to form a peil' of ribs, said shield also having an integrally-for1ned inwardlyprojecting rib intermediate its ends, the two outer ridges of said -coil form respectively engaging Within e faces which are substantially cylindrical and coaxial with said coil form and said shield.

6. In combination, a onefpyiece hollow cylindrical shield, atubular form, and a plurality of coil sections wound on said tubular form in longitudinal spaced-apart relation, said shield adapted to substantially enclose said coil sections and being provided with one or Imore integrallyformed ribs projecting radially inward so as to respectively Contact said form in the spaces between said coil sections.

7. In a torque measuring device for a hollow rotatable power-transmitting member, the combination of a torque tube within and secured to said power-transmitting member, a rotating coil assembly and a stationary coil assembly within said torque tube, said rotating coil assembly cormprising. a tubular support securely positioned to rotate coaxially with said torque tube, a coil on said support, said coil having a pair of longitudinally spaced-apart sections, a one-piece hollow cylindrical coil shield secured to said support,

said shield substantially enclosing said coil and being provided with three integrally-formed ribsmovement therebetween, means securing said second support against rotation, and means act- -ing to prevent relative longitudinal movement between said two supports during rotation-i, oi said rotating coil assembly.

8. A torque measuring device according to claim 7 in which said last-mentioned means includes a resilient member.

9. A torque measuring device according to claim 7, further comprising three annular ridges on said first-mentioned coil support, said ridges being respectively located outside the ends of and between said rotating coil sections, the ribs of said coil shield being spaced to respectively engage said ridges. Y

10. A torque measuring device according to claim 7, in which said coil shield is provided with an outwardly-hanged portion engaging said torque tube, said anged portion having a niche in the periphery thereof, further comprising a projection on the inner surface of said torque tube and receivable in said niche, a lead connected to said projection. a lug on said anged portion, and means connecting said lead to said lug.

ll. A torque measuring device according to claim 7, in which said means securing said second support against rotation is formed with a cylindrical portion', in which said second support is provlded'with a tubular insert, and in which said means acting .to prevent relative longitudinal movement between said two supports during rotation of said rotating coil vassembly includes a tubular spring holder secured to one end of said tubular insert and engaging the cylindrical p0rtion of said securing means in slidable telescoping relation, and a spring within said spring holder engaging the cylindrical portion of said ,securing means.

12. A coupling device according to claim 1 in wardly-anged portion on the corresponding ridge of said tubular supportv adapted to be received within the cut-out portion of said onev rib, and means for securing together said one rib and said ilanged portion.

CLIFFORD A. SHANK. 

